1. Technical Field
This invention relates to pressure operated valves used in earth wells. More particularly, the present invention is a sleeve type valve releasably connected in a housing, which is operated by pressure to close and be expended from the housing.
2. Background Information
A sealing plug is usually installed in a pressure operated packer or well tubing to close the packer or tubing and permit pressurization of tubing connected to the packer to set the packer in casing in an earth well. An example of one such device is shown by U.S. Pat. No. 3,042,116 to Sharp et al. This patent discloses use of an adapter to connect an expendable sealing plug in a well packer and releasable latching means for holding the expendable sealing plug in the adapter. When connected in the packer, the plug closes the packer to through flow and there is no flow passage through the plug. The packer is lowered to setting depth with the plug connected in the packer and the plug is expended by application of tubing weight after use.
When lowering a packer with a sealing plug installed, all liquid displaced by lowering the packer and tubing into the well flows from below to above the packer through the small annular space between the packer and casing in the well. Usually, the packer and tubing are lowered rapidly into the well casing causing displaced liquid volume to be great, resulting in high liquid velocities through the small annular space. As most of the displaced liquids contain solid particles, the elastomeric sealing element on the packer may be abraded away or damaged by high velocity particles so that it will not seal in the well casing properly when the packer is operated to set.
Another example of a similar plug is shown in U.S. Pat. No. 3,216,504, "Plug for Well Conductors" to Roark. This plug is releasably lockable in a well packer having a latch head and is installed in the packer set in casing by lowering on a setting tool on tubing. This plug may be retrieved on tubing using the same setting tool or expended from the packer by application of tubing weight.
Running tubing from surface into a well to install or expend a sealing plug from a packer is a time consuming and expensive operation, especially if long lengths of tubing must be run to reach a packer set deep in a well.